PLANT PROPAGATION US Level 2 Horticulture Science

Contents Asexual vs sexual Propagation Asexual vs sexual Sexual propagation Sexual propagation Seed sowing Flower structure Asexual propagation (overview) Asexual propagation Division Layering Tissue culture Cuttings Budding and Grafting Plant Breeders Rights

Propagation: DEFN: Plant propagation is the process of creating new plants Plant propagation can also refer to the artificial or natural dispersal of plants. Types of Propagation:Things that are not examples of Propagation

Asexual and Sexual Propagation Asexual Propagation - using one parent plant to produce a new individual that is a clone (genetically identical) Key words: offspring, new individuals, parent plant(s), Sexual Propagation – recombination of the genes to produce a new individual that is a genetically different (also known as sexual reproduction) In Angiosperms -This always involves flowers and always results in seed. In Gymnosperms/ ferns and Moses this results in spores Question – if a plant self pollinates is it sexual or asexual propagation?

Examples of Propagation Techniques SexualAsexual SeedLayering Tissue Culture Grafting Budding Stem Cuttings Leaf cuttings Root Cuttings Bulbs Corms Runner Rhizomes Crown division Stolons

Seed sowing - Contents To understand seed sowing technique we will be looking at: Seed structure Germination Respiration Seed requirements Seed Dormancy Seed Vigour and Viability Seed Sowing Menu

To have sex or not to have sex? Advantages of Sexual PropagationAdvantages of Asexual Propagation Relative to many asexual propagation techniques – seed sowing is inexpensive Produces large quantities of new plants Can easily be mechanised Is the only method of producing new varieties (essential for plant breeders) Creates genetic variation within a crop aiding with disease and pest control Genetic variation adds to landscape contrast and beauty Can be stored Controlled ‘hybridisation; of plants can give increased ‘hybrid vigour’ No genetic variation resulting in a more consistent product. Bypass the immature phase Can produce plants that are not easily propagated from seed

Hybrid vigour When two varieties of plant are crossed together (sexual propagation) the combining of different genetics results in a plant that is hetrozygous for many genotypes. This often means that a particular trait receives both of the varieties traits

Seed sowing – seed structure Three parts to a seed Seed coat Endosperm Embryo ‘A seed is a plant in a box with it’s lunch’ Seed Sowing Menu

Seed sowing – seed structure Seed coat -the outer covering of a seed helps protect the embryo from injury and drying out. Seed coats can be thin and soft as in beans or thick and hard as in walnuts or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These are often the first parts visible when the seed germinates. Embryo – the ‘baby’ plant. Seed Sowing Menu

Two different situations: Cotyledon(s) appear above ground as first leaves (seed leaves) Cotyledon(s) remain below the ground

Seed sowing – Seed Structure There are two types of plants that produce seeds: Monocotyledons and Dicotyledons Seed Sowing Menu

Seed Structure Seed Sowing Menu

Germination Starts when the seed begins to absorb water Ends when the new plant is able to get all its’ energy from photosynthesis.

Germination – the process 1. The seed absorbs water until it swells and smoothens its exterior wrinkles. 2. Swelling continues until the coat of the seed bursts open. 3. Food stored in cotyledons or endosperm soaks up water and soluble substances dissolve in it. 4. Respiration begins thus energy and raw materials are supplied by food for cell division and growth. 5. A radical appears first and then a pumule.

Respiration During respiration (in plants and animals) energy is released from sugar (glucose) by a series of chemical reactions. The sugar is broken down into carbon dioxide and water in a process which uses oxygen.

Respiration in seeds INPUTSOUTPUTS

Seed requirements List the inputs all seed require to germinate Match your list to the following. Allows seed to swell and break seed coat Required for respiration Speeds up the various chemical processes

Seed dormancy Dormant seeds are seeds that are still alive but when the seed is supplied all that it needs to germinate, - it doesn't. The seed is asleep, waiting for the proper time to awaken. Seed dormancy aids a species' survival by delaying germination so that 'overall germination' is dispersed over time.

Seed Storage Germination needs water. warmth and oxygen Seed storage needs (the opposite) Cool and dry! Why can we not store seeds in a oxygen free environment?

Seed Sowing Summary Seeds don’t get re-assessment opportunities. Once they begin to germinate they either survive or die. Seeds need the WOW factor to survive (water oxygen, warmth). Soil, light, CO 2 are only for ‘grown-up’ seeds A seed is a plant in a box with it’s lunch – but no dinner – if a seed is in the packet too long it will run out of lunch and die.

End – Seed Sowing Back to Main menu

Asexual Propagation (outline) We will be investigating 5 methods of asex prop. 1. Cuttings 2. Grafting and Budding 3. Division 4. Layering 5. Tissue Culture Note: horticulturalists have created ways of undertaking asexual propagation that don’t occur in nature To begin to understand asexual prop we need to understand meristematic cells

Importance of Meristematic cells Meristematic cells – plant cells that are capable of dividing to create new plant cells that are unspecialised Cambium layer – contains the meristematic cells Unspeciallised cells are able to turn into any type of plant cells.... Eg xylem Phloem Epidermal

Location of cambium layer

How does crown tissue work. The crown area of a plant contains both stem and root tissue and corresponding cells such as xylem, phloem and epidermis Theses cells are already speciallised and will go onto create more of the same specialised cells. Crown of rhubarb plants

Seed sowing To understand seed sowing technique we will be looking at: Seed structure Germination Respiration Seed requirements Seed Dormancy Seed Sowing Menu

Seed sowing – seed structure Three parts to a seed Seed coat Endosperm Embryo ‘A seed is a plant in a box with it’s lunch’ Seed Sowing Menu

Seed sowing – seed structure Seed coat -the outer covering of a seed helps protect the embryo from injury and drying out. Seed coats can be thin and soft as in beans or thick and hard as in walnuts or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These are often the first parts visible when the seed germinates. Embryo – the ‘baby’ plant. Seed Sowing Menu

Two different situations: Cotyledon(s) appear above ground as first leaves (seed leaves) Cotyledon(s) remain below the ground

Seed sowing – Seed Structure There are two types of plants that produce seeds: Monocotyledons and Dicotyledons Seed Sowing Menu

Seed Structure Seed Sowing Menu

Germination Starts when the seed begins to absorb water Ends when the new plant is able to get all its’ energy from photosynthesis.

Germination – the process 1. The seed absorbs water until it swells and smoothens its exterior wrinkles. 2. Swelling continues until the coat of the seed bursts open. 3. Food stored in cotyledons or endosperm soaks up water and soluble substances dissolve in it. 4. Respiration begins thus energy and raw materials are supplied by food for cell division and growth. 5. A radical appears first and then a pumule.

Respiration During respiration (in plants and animals) energy is released from sugar (glucose) by a series of chemical reactions. The sugar is broken down into carbon dioxide and water in a process which uses oxygen.

Respiration in seeds INPUTSOUTPUTS

Seed requirements List the inputs all seed require to germinate Match your list to the following. Allows seed to swell and break seed coat Required for respiration Speeds up the various chemical processes

Seed dormancy Dormant seeds are seeds that are still alive but when the seed is supplied all that it needs to germinate, - it doesn't. The seed is asleep, waiting for the proper time to awaken. Seed dormancy aids a species' survival by delaying germination so that 'overall germination' is dispersed over time.

Seed Storage Germination needs water. warmth and oxygen Seed storage needs (the opposite) Cool and dry! Why can we not store seeds in a oxygen free environment?

Seed Sowing Summary Seeds don’t get re-assessment opportunities. Once they begin to germinate they either survive or die. Seeds need the WOW factor to survive (water oxygen, warmth). Soil, light, CO 2 are only for ‘grown-up’ seeds A seed is a plant in a box with it’s lunch – but no dinner – if a seed is in the packet too long it will run out of lunch and die.

End – Seed Sowing Back to Main menu

cuttings Stem cuttings are the second most widely used form of propagation in horticulture. (Number one is seed)

Semi- hardwood cuttings of Forsythia Leaf cuttings of petunias Hardwood cuttings of grape vines Tip (softwood) cuttings of Hydrangeas

Division Examples of Asexual Examples of Sexual

Grafting Examples of Asexual Examples of Sexual

Layering Examples of Asexual Examples of Sexual